JDMK Services and Development Tools

 

Besides the base components of JDMK several services and tools exist to simplify the development of management applications and agents (cf. figure 3).

  

Figure 3: JDMK Services and Development Tools

Repository Service is used for the registration process. Beans may be registered either as volatile or persistent within the CMF.

With the aid of the Filtering Service it is possible to define filtering rules selecting all M-Beans which are registered at a CMF that match the filtering rule. Such rules may be defined over methods, attributes with their concrete values and over object names and their single parts.

To determine the properties and methods which are supported by an M-Bean the Metadata Service, based on the Java Reflection API, can be used. The Metadata, the Repository and the Filtering Service are called Base Services of the CMF.

The Discovery Service is used to detect all active CMFs. Therefore an IP-broadcast is sent by the service and all CMFs that have registered a so-called Discovery Responder reply to the broadcast message.

  

Figure 4: The JDMK Management Applet (M-Let) Service

Agent and manager are able to use different Class Loaders -- even in parallel -- to load the implementation classes from local or remote sites. To take advantage of native (non-Java) dynamically linked libraries in M-Beans the Library Loader Service may be used. The Class and Library Server is available as a local or remote repository for class files and libraries. This server can be used either as a stand-alone application or - because it is realized as an M-Bean as well - registered with a CMF.

M-Let, Launcher and Bootstrap Service are used for the dynamic extension of agents, for update mechanisms and for bootstrapping.
The M-Let Service (Management Applet Service) offers the possibility to download and configure M-Beans dynamically. For this purpose a new HTML tag (<MLET>) is defined. The M-Let Service operates according to the following steps (see also figure 4):

1.

The M-Let Service loads a HTML page from an URL from which it can obtain all the necessary information about the Beans to load (i.e. names, objects, code repository).

2.

By using this information the M-Let Service is able to download the implementation classes of the M-Beans and to instantiate them.

3.

Afterwards, the M-Let Service must register them with the CMF.

It is also possible to put version information inside the (<MLET>) tag and to use the M-Let Service for versioning.

The Bootstrap Service, which is implemented as a stand-alone Java application, simplifies the distribution and instantiation of JDMK agents. This service is used to download implementation classes of an agent from a local or remote server. Therefore the Bootstrap Service initializes the CMF, starts the M-Let Service, loads the necessary classes, initializes, registers and starts all the required M-Beans and services of the agent.

Two compilers, mogen and mibgen, are delivered with JDMK as development tools. The mogen is used to create C-Beans from M-Bean .class files.
For developing an JDMK based SNMP Agent for a device mibgen can be used. If SNMP-MIB files are available for the managed device, the mibgen Compiler is able to use them to create M-Beans representing the MIB. The M-Beans have to be enlarged with functions e.g., implementing access to resources of the managed system.